Telephone-exchange system.



H P. CLAUSEN. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR. 1. 1915.

Pateilted June 19*, 1917.

//7 Men/0k. Henry A flan/sen.

UNITED STATES PATENT oEEIoE.

HENRY P. CLAUSEN, 0F MOUNT VERNON, NEW YORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent. Patented June 19 1917,

Application filed April 1, 1915. Serial No. 18,459.

To all whom it may concern:

Be it known that I, HENRY P. OLAUSEN, a citizen of the United States, residing at Mount Vernon, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to an improved telephone signaling system, and its object is to provide simple and efiicient means for automatically determining the connection of a device with one end or the other of a circuit uniting two telephone stations. More particularly, my object is to provide automatic shifting mechanism for controlling the connection of calling current with the circuit, so that the calling current may automatically be directed toward that par: ticular one of the two united stations which needs to be signaled in order to bring about the completion of the telephonic or conversational circuit.

In the ordinary progress of a connection between two telephone stations the link circuit at the central oflice first acts or is manipulated to connect with the calling station. The connection is then extended, through the link circuit to the called station, and that station is signaled by the application of calling current to the link circuit. But occasionally it is necessary to ring back over the circuit to signal the calling station-as, for instance, when the callin subscriber hangs up just before the calle subscriber answers and has to be recalled, or when the called subscribers line is found to be busy, and the calling subscriber asks that he be notified as soon as the called line becomes available. I In such cases it is desirable that the connecting circuit have means for throwing calling current back toward the calling subscriber, and it is principally toward the provision of means for accomplishing this result with the minimumof effort that my invention is directed.

The accompanying drawing illustrates my invention applied to a connecting cord circuit adapted for uniting two subscribers lines. In the drawing I have shown two telephone lines extending from stations A and B to a central ofiice C, where the lines terminate upon spring jacks and are provided with line signal apparatus. The line vcircuits are of a well known sort, and do not require particular description. Each of the telephone stations has a call receiving device or bell p and a telephone switchhook T which closes the circuit of the lines when the telephone'receiver is lifted. Each line circuit is adapted to have its connection extended through the medium of the spring Jack upon which it terminates, and a 00- operating plug of the cord circuit which is adapted to be inserted in the spring jack.

In the embodiment shown, the connecting cord circuit is of the two-conductor type, the two conductors 1 and 2 terminating upon the tip-contact and the sleeve contact of the answering and calling plugs a and 7) respectively. In each of these conductors a condenser c is interposed to render thesame conductively discontinuous, and current from the battery d is fed to each half of the -Qthrough the winding of the sleeve supervisory relayv e, and the grounded pole of the battery connects with the tip strands 1 through the tip supervisory relay f. In the calling half of the cord circuit the free pole of the battery has connection with the sleeve strand through the sleeve supervisory relay g, and the grounded pole has connection with the tip strand through the tip supervisory relay k.

The circuit of the answering supervisory lamp 8 is adapted to be closed in a back contact of the answering supervisory relay 7 and in front contacts ofeither the answering supervisory relay 6' or the calling supervisory relay 9; andin like manner the circuit of the calling supervisory lamp '2? is adapted to" be closed in the front or alternate circuit is equipped with a ringing key Z which controls the application to the circuit of current from a generator or source of calling current m. In the normal condition. of the circuit the actuation of the ringing key Z causes current from the generator m to be applied to the calling plug 6, and through it to the bell at the called subscribers station. But to enable calling current to be directed either way upon the circuit, and thus ring the bell at either of the connected stations, I provide shifting switch mechanism which acts automatically to direct the calling current to either of the two connected stations which may happen at the time to have its telephone on its hook.

To accomplish this result, I provide, in the embodiment of the invention here illustrated, a shifting relay a with a number of sets of contact springs. For clearness in illustration, and to avoid confusing the circuit, I have represented these sets of con tact springs a, n a a a, and n as being distributed at different points in the circuit; but it will be understood that they are all operatively associated with the magnet of the relay a. In order to indicate this operative association of the distributed sets of contacts with the magnet a, and to show the direction of movement of the main switch spring of each set upon the energization of the relay, I have illustrated in association with each of the sets or, n, n, and a, a fragment of the magnet pole.

Each of the sets of switch springs n n 71- and n consists of three contact pieces, the main contact piece being adapted to normally make contact with one of the associated contact pieces and to break this contact and come into engagement with the other contact piece when the relay a is energized. In the normal position of the parts the sets of contacts a a n, and a, are adapted to connect the lefthand or the answering plug with the left-hand side of the cord circuit and the right-hand or the calling plug with the right-hand side of the circuit. lVhen the relay a is energized, these sets of contacts move into their alternative positions, which 'movement serves to reverse the connection of the two plugs with the halves of the connecting cord circuit; that is, the energization of the shifting relay it connects the answering plug a with the right-hand or calling side of the circuit, and connects the calling plug l) with the left-hand or answering side of thecircuit.

At the same time the movement of the two other sets of contacts a and n associated with the shifting relay 1, brings about the shifting of the answering supervisory relay f from its normal connection with the lefthand side of the cord circuit, to a con nection with the right-hand side of the circuit; and also shifts the calling supervisory relay 7r from its normal connection with the right-hand side of the cord circuit to a connection with the left-hand side of the circuit. Inasmuch as the actuation of the asso ciated sets of contacts a and has at the same time brought the lefthand, or answering side of the circuit into association with the tip of the calling plug and the righthand, or calling side into association with the tip of: the answering plug, this shifting of the circuits of the supervisory relays and h, just described, serves to keep the answering supervisory relay f associated with the answering plug and the calling supervisory relay 7t associated with the calling plug, so that these relays are unaffected by the actuation of the shifting relay n in the matter of their control by the calling line and called line, respectively.

In the embodiment of the invention that I have illustrated, the shifting relay is responsive to the condition of use or disuse of the telephones at the two connected stations. The control exercised by the two stations over the shifting mechanism is through the medium of the two supervisory relays f and 72 the energizing circuit of the shifting relay a being arranged to be completed in a back or resting contact of the answering supervisory relay and in a front or alter nato contact of the calling supervisory relay /1. hen both supervisory relays are unenergized the circuit of the shifting relay n is open in contacts of relay h. \Vhen both supervisory relays are energized, the circuit of the shifting relay is open in contacts of the relay f. In either case the conditionof the link circuit is normal, and such that calling current, when applied, is directed to the calling plug 7). But when the answering supervisory relay f is unenergized and the calling supervisory relay h energized, the circuit of the shifting relay a is closed and that relay is operated to shift the circuits in the manner described and to cause calling current, when applied, to be directed to the answering plug.

The particular embodiment of my invention which I have illustrated and described operates as follows: YVhen the subscriber at station, A takes his telephone from its hook, the line signal associated with his line at the central ofl ice is displayed, and the operator responds to the signal by inserting the answering plug a into the corresponding spring jack. This completes a circuit for the flow of current through the answering supervisory relays c and f by way of the calling subscribcrs station, a part of the current flowing by way of the relay 0 being diverted through the cutoff relay of the calling line to keep that relay operated while the answering plug is in the jack. The actuation of the sleeve supervisory relay 6 closes the answering lamp circuit in associated contacts, but the operation of the tip supervisory .relay n.

When the operator has ascertained that the calling subscriber desires connection with the subscriber at station B, she inserts the calling plug 6 into the spring jack of the line extending to that station. This act completes the circuit of the sleeve supervisory relay 9 by way of the sleeve conductor of the calling cord and the winding of the cutoff relay of the called line. But inasmuch asthe telephone is on its hook at the called station, the tip supervisory relay k is not energized, and therefore the circuit of the calllng lamp is closed in front contacts of the relay 9 and back contacts of therelay h, and the lamp is lighted. Y

In order to signal the called subscriber, the operator presses the calling key Z. This brings the source of calling current m into connection with conductors extending to the normal or resting contacts of the sets n and n of switch springs of the shifting relay, and also into connection with conductors eX- tending to alternate or normally open contacts of the sets a and n of shifting relay switch springs associated with the answerlng cord. As the circuit of the shifting relay a under the conditions described is open in the contacts of both tip supervisory relays f and h, the shifting springs are in their normal condition, and the current from the generator or source of calling current m flows to the calling plug and thence to the called station B where it rings the bell. The called subscriber, responding to the ring, takes h1s telephone from its hook, thus permlttlng current to flow back over the other side of the circuit and through the tip supervisory relay it, thus causing the energization of that relay. However, this does not close the c1rcu1t of the shifting relay,.as the c1rcu1t 1s held open in contacts of the answering supervisory relay 7 as long as thecalling subscrlber has his telephone off thehook.

But it may be that the called subscr ber has been slow in responding, that just before he takes his telephone from its hook the call ing subsc'ribergets tired waiting and hangs up, and the called subscriber, finding no one on the line, signals the operator and requests her to ring the party who was calling hlm. In such case the operator merely presses her ringing key Z again. This time the calling current, instead of flowing to the called subscribers station as it did when the ringing key was first pressed, now flows back over the circuit to the calling subscribers station and rings the bell at that station. The reason is that the telephone at the callingstation being on its hook and the telephone at the called station off its hook, answering supervisory relay fis denergized, while calling supervisory relay h is energized and the circuit of the shifting relay n is completed. The shifting relay therefore has moved all of its switch contacts into their alternative positions, thus opening the previously existing path for the flow of calling current to the calling plug, and. closing, in contacts a and a a path for this current to flow to the answering plug.

'The shifting contacts at the same time that they disconnect the calling plug from the calling half of the cord circuit, connect it with the answering half of the cord circuit, so that whether the cord circuit be in its normal or shifted condition, its continuity is preserved. Furthermore, the sets of contacts a and n of the shifting relay at the same time shift the connections of the supervisory relays f and it, so that each relay may be maintained in connection with the particular.subscribers station to the condition of which it is intended to be responsive, otherwise the shifting of the circuit effected in the contacts W, n, n and 17. Would reverse the connection of the supervisory relays f and h with the two connected telephone stations, which would cause the supervisory relay 7", now being associated with the called station, to become energized, and the supervisoryrelay h, now being associated with the calling station, to become deenergized, thus breaking the circuit of the shifting relay n and causing the shifting contacts to return to normal.

7 In order to avoid altering the states of deenergization and energization, respectively, of the supervisory relays f and h in the shifting of the'circuits, I have found it desirabl'e'to use contacts of the make-beforebreak type in the sets 01/ and n of shifting switch springs, -andto cause the main or lever spring of the set M to break quickly from its resting contact and to have a fairly large range of movement before it engages its front contact. By thus arranging the contacts the relay h is held in connection with the closed circuit through the called subscribers station, and the relay 7"" is kept I from having its circuit closed over this path.

WVhen in response to the application, of calling current to the calling subscribers line, the subscriber at the calling station takes his telephone from its hook, the energization of the supervisory relay 7 opens the circuit of theshifting relay 1, and the cord circuit resumes its normal condition.

In case the condition should arise where the calling subscriber, finding the called line busy, requests the operator to call him when the called line becomes available, the operator may do this without'reversing plugs or without pressing any special key. She

merely leaves the answering plug in the jack of the calling subscribers line, the calling subscriber having hung up, and tests the called line from time to time until she finds it free. She then inserts the calling plug into the called line jack and presses the ringing key Z. Neither calling nor called subscriber being at his telephone, relays f and k are deenergized, and the circuit through shifting relay a is open. Conse quently ringing current is directed to the called subscribers station. When the called subscriber answers the operator again presses the ringing key Z. This time, supervisory relay 72. being energized and supervisory relay f being deenergized, the shifting relay is operated and the ringing current is directed to the calling subscribers station. Thus the ringing current is automatically directed toward the station Where the subscriber is not at his telephone.

It may also be seen that by virtue of this organization of circuits and apparatus, either plug may be used indiscriminately for answering, the shifting mechanism operating automatically to direct calling current toward that plug which is associated with the line where the telephone has not yet been taken from its hook.

I have shown my invention applied to a particular type of line and connecting cord circuit, but it will be understood that this is merely for the purpose of illustration, and that the invention is readily applicable to line and connecting circuits of types other than the two-wire type of the circuit shown, and to circuits in which connecting appliances other than plugs and jacks are used for completing connection with the telephone lines.

lVhat is claimed is:

1. In a telephone system, the combination with two telephone stations, of a circuit connecting said stations, a source of calling cur rent, a switch for applying calling current to the circuit, and an automatic device for directing the flow of the current so applied to one or the other of said stations.

2. In a telephone system, the combination with two subscribers lines, a link circuit for connecting said lines, a source of calling current, a manually controlled key for applying current from said source to the link circuit, and an automatic switching device jointly controlled from the two subscribers stations for directing the flow of the current so applied to one or the other of said stations.

3. In a telephone system, the combination with two telephone stations, of a link circuit for uniting the stations, a supervisory relay in the link circuit for each of the stations, a source of calling current, an electromagnetic switch for directing the calling current to either end of the link circuit to call the associated station, and an energizing circuit for the electromagnetic switch including contacts of both supervisory relays.

4. In a telephone system, the combination with a pair of connecting cords, of a source of calling current, a switching device adapted in its alternative positions to direct the application of said source of calling current to one or the other of said connecting cords, and supervisory relays associated with said cords adapted to control the operation ofsaid switching device.

5. In a telephone system, the combination with two telephone stations, of a link circuit for uniting the same, a supervisory relay in said link circuit for each of said stations, a source of calling current, an electromagnetic shifting switch adapted to direct the application of said source of calling current to either end of said link circuit to call the associated station, and an energizing circuit for the said electromagnetic shifting switch including a normally closed contact of one supervisory relay and a normally open contact of the other supervisory relay.

6. In a telephone system, the combination with two telephone stations each provided with a call receiving device and a switchhook, of a circuit uniting said stations, a source of calling current, a relay controlling the application of calling current from said' source to one or the other of said stations, and an energizing circuit for said relay controlled jointly by switchhooks of the two united telephone stations.

7 In a telephone system, the combination with two telephone stations each having a call receiving device and a switchhook, of a pair of connecting cords for uniting said stations, a source of calling current, a key for controlling calling current from said source, a shifting relay adapted in its alternative positions to direct calling current controlled by said key to one end or the other of said pair of connecting cords, a supervisory relay associated with said pair of connecting cords for each of the united telephone stations, said supervisory relays being under the control of the switchhooks of the corresponding stations, and an energizing circuit for said shifting relay controlled jointly by said supervisory relays.

8. A telephone exchange system comprising two telephone lines, a link circuit connecting said lines, a supervisory relay normally in operative relation with one end of the link circuit and controlled over the telephone line connected with that end, and mechanism for switching the supervisory relay into operative relation with the other end of the link circuit whereby it is controlled over the telephone line connected with that end.

9. A telephone exchange system comprising two subscribers lines, a supervisory relay normally in operative relation with one end of the link circuit and controlled In witness whereof, I hereunto subscribe over the telephone line connected with that my name this 80th day of March, A. D. 1915. 10 end, and a relay jointly controlled from the 4 two stations for switching the supervisory HENRY P. CLAUSEN. relay into operative relation with the other end of the link circuit whereby it is con- Witnesses:

trolled over the telephone line connected E. EDLER,

with that end. K. L. STAHL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). G. 

